This research program is concerned with the elucidation of the mechanism of the genetic control of cellular differentiation, in a relatively simple model developmental system leading to dormant spore formation in Bacillus subtilis. It is proposed to construct gene cloning systems from B. subtilis temperate bacteriophages for the isolation and analysis of proteins specified by sporualtion genes. It is also proposed to define, isolate and characterize sporulation genes by DNA cloning procedures. Portions of the early sporulation genes will undergo DNA sequence analysis to determine nucleotide signals which may control their expression.